The present invention relates to a manufacturing method of an optical fiber ribbon in which a plurality of optical fiber core cables are arranged in parallel and coupled, a manufacturing device for an optical fiber ribbon implementing the manufacturing method and an optical fiber ribbon manufactured with the manufacturing method.
Conventionally, an optical fiber ribbon as shown in FIG. 14 has been proposed, in which a plurality of subunits 53, each of which are formed by covering a plurality of optical fiber core cables 51 with a covering portion 52 in an entire length in a longitudinal direction, are assembled. The plurality of subunits 53 are integrally fixed over the entire length in the longitudinal direction by a coupling/covering portion 54. An optical fiber ribbon 50 thus formed can be divided into the separate subunits 53 by breaking the coupling/covering portion 54. The optical fiber ribbon 50 has good workability regarding connection of the respective subunits 53.
Incidentally, recent growth in optical fiber cable network has become a factor to increase demands for efficient use of conduits and the like as an optical fiber cable network infrastructure, cost reduction of network construction goods themselves, and cost reduction of cabling (construction), and so on.
For the efficient use of conduits and the like, the optical fiber cables, which are main goods used in constructing the optical fiber cable network, need to become thinner and more densified. Further, for the cost reduction of network construction goods themselves, a manufacturing cost of the optical fiber cables needs to be reduced. Also, for the cost reduction of cabling (construction), the optical fiber cables need to be handled easier, in addition to being made thinner and more densified.
In order to thin and density each of the optical fiber cables, one needs to be put into practice, in which packaging density of optical fiber core cables in the optical fiber cable is increased, so that an outer diameter of the optical fiber cable becomes smaller even when a number of optical fiber core cables used remains the same. The above-described optical fiber ribbon 50 is difficult to be deformed in a width direction and warps greatly by being curled and folded; therefore, the configuration thereof is not suitable for being used as an optical fiber cable.
As an optical fiber ribbon suitable for being used as an optical fiber cable, as shown in FIGS. 15A and 15B, an optical fiber ribbon 60 is disclosed in Japanese Patent No 4143651, in which a plurality of optical fiber core cables 61 are arranged in parallel and the neighboring optical fiber core cables 61 are coupled to each other by coupled portions 62 at given intervals in the longitudinal direction.
The optical fiber ribbon 60 in which the optical fiber core cables 61 are coupled at given intervals is deformed easily in the width direction, and warp caused when being curled and folded can be suppressed as much as possible. Accordingly, the optical fiber ribbon 60 can be thinned, densified and lightened when applied as an optical fiber cable, and is suitable for being used as the optical fiber cable.
In order to reduce the manufacturing cost of optical fiber cables, it is effective to configure one optical fiber ribbon with as much optical fiber core cables as possible. For example, to configure 200-core optical fiber cable, 50 sheets of optical fiber ribbons are required when using 4-core optical fiber core cables. However, only 25 sheets of the optical fiber ribbons are required when using 8-core optical fiber core cables, and only 10 sheets of the optical fiber ribbons are needed when using 20-core optical fiber core cables. In other words, the more the number of cores of the optical fiber core cables is used, the less the number of sheets of the optical fiber ribbon is required upon configuring the optical fiber cable. This can reduce the manufacturing cost of the optical fiber cables.
The optical fiber ribbon 60 as mentioned above, in which the neighboring optical fiber core cables 61 are coupled to each other by the coupled portions 62 at given intervals in the longitudinal direction, is effective to meet the above demands. However, regarding the optical fiber ribbons as such, distinguishability of each of the optical fiber core cables becomes a problem upon handling.
That is, in facilities in the optical fiber cable network, a technique is generally used in which optical fiber core cables are connected with each other in a bundle of plurality of cables to enhance construction efficiency. For this reason, a fusion splicer for collectively connecting a plurality of optical fiber core cables and a mechanically transferable (MT) connector which is an optical connector for collective connection of multi-core cables, and the like are used. However, a number of connection cores of the connectors does not necessarily coincide with a number of the optical fiber core cables arranged in the optical fiber cable. Further, it is essential that connection can be made by a unit of number of cores made by dividing the total number of cores. From this aspect, the optical fiber ribbon configured by a plurality of subunits as described above is effective upon cabling.
Moreover, in order to improve the distinguishability of each of the subunits, coatings of the optical fiber core cables are colored with an ultraviolet curing resin and the like so that the cables are distinguished by colors. However, a number of available colors is not infinite and only a limited number of colors is used to keep distinguishability. Accordingly, the subunits are distinguished from each other by combination of colors of the optical fiber core cables configuring the subunits.